Unbind CS if connection is not created within 15 seconds.

This CL adds a check to ensure that connection creation occurs within 15 seconds after binding to that ConnectionService. If the connection/conference is not created in that timespan, this CL adds logic to manually unbind the ConnectionService at that point in time. This prevents malicious apps from keeping a declared permission in forever even in the background. This updated CL includes a null check to avoid a NPE that occurred in the first iteration of this change.

Bug: 293458004
Test: manually using the provided apk + atest CallsManagerTest
Flag: EXEMPT Security High/Critical Severity CVE
Change-Id: Ia47e0a6574a9bd61529ce154a09a5d1e836dbd19